Research On The Detection Of Elastic Wave Velocity And Crack Depth Of Concrete Structure Based On ITECS Technology

Concrete material is widely used in engineering construction, its quality directly affect the safety of engineering structures. Therefore, control of the quality of concrete is very important. It is necessary to build a platform for non-destructive testing system. As technology advances, Time and effort consuming non-destructive testing methods cannot meet the increasingly precise detection needs. In Japan, a high precision, powerful impact-echo no n-destructive testing technology-iTECS emerged.11years of engineering practice has proved its great features. I believe iTECS technology can also provide high-efficiency,high-precision,low-cost leaping development for the application of non-destructive testing of concrete in china.This paper relying on the research projects of iTECS non-destructive testing technology. Select laboratory precast elements and bridge members, using theoretical analysis, field testing, data processing and model building etc. The methods of accurate detection the elastic wave velocity and crack depth were studied. Make the influence of different impact duration, impact force and the existence of rebar for sensitivity analysis. The main research works as follows:Through testing the elastic wave velocity of site concrete structures, Propose to the method of adjust the hammer and sensor interval to ensure detection accuracy,which has been verified. Therefore, to ensure measurement accuracy, set at least four different intervals is necessary.Take cracks in the concrete structure as research object, Based on the symmetrical layout of hammers and sensor detects the vertical cracks, put forward improvement suggestion. When the detection conditions are restricted, put forward new method. Analogy the detection principle of vertical cracks, put forward the method of detect inclined crack, and then give the calculation formula of depth, angle and extension length of inclined crack. Finally, through making a specimen verify the above methods and calculation formulas are feasibility.Contrast the difference of p-wave velocity under impact load between plain concrete beam and reinforced concrete beam, and research the rule of response spectrum of reinforced under different impact duration by using ABAQUS finite element software. Results show that appropriate increase impact duration can reduce the influence of steel to p-wave velocity test results. Through the fem simulation of knock hammer and sensor symmetrical layout and asymmetric layout testing methods under different crack depth, get the expected results. Through contrasting the results of site test data and simulation results find that both of them have the same rule, and different impact force have little effect on calculation results of crack depth. Finally, Research the response of cracks under the different impact duration by simulating, obtained the measure of clearly identify defects.